Press unloader



March 16, 1943. n c. BUTTERFIELD 'Y 2,314,123

PRESS UNLOADER Filed May 17, 1940 5 Sheets-Sheet l March 16, 1943.v l K. c. BUTTERFIELD 2,314,123

PRESS UNLOADER Filed May 17, 1940 5 sheets-sheet 2 March 16, 1943. K. c. BUTTERFIELD 2,314,123

` PRESS iJNLoADER Filed May 17, 1940 s sheets-'sheet s K. C, BlJTTElRI-'IELDA March 16, 1943.

' PRESS UNLOADER In 32 IQ Mardi 16, 1943- l n c. BUTTERFIELD 2,314,123

- -PREss UNLOADER y Filed may 17. `1940r 5 Smets-sheet 5 liv Patenied Mar. 16, 1943 PRESS UNLOADER.

Kenneth Carlyle Butterfield, Grand Rapids, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application May 17, 1940, Serial No. 335,690

6 Claims.

This invention relates to a press unloader and more particularly to a press unloader for positively removing metal stampings from the press after the stamping operation.

It is well known that accidents frequently occur in the operationl of sheet metal stamping presses. Among these accidents are those which occur when the operator reaches between the dies of the press and the press is inadvertently tripped. It is an object of this invention to remove this hazard of sheet metal press operation. This object is achieved by a press unloader which will efciently and positively remove the iinished tmetal stamping from the press. In particular the invention Vcontemplates a press unloader which, after the stamping operation is completed, reaches into the press, grasps the stamping and removes the same.

In the drawings:

Fig. 1 is a side elevational View of the press unloader with the press closed.

Fig. 2 is a top plan view of the press unloader with the press closed. f

Fig. 3 is a front elevational view, partly in ver- -tical section, of the press unloader as viewed from th'rght of Fig. 2.

Fig. 4 is a side elevational view of the press unloader during the initial upward movement of the ram. 2

Fig. 5 is a side elevational View of the unloader with the press fully opened at the end o-f the press unloading stroke.

The press unloader comprises a pair of channel iron tracks I and 2 which are inclined slightly forwardly and downwardly toward the press. The tracks I and 2 are supported upon the rigid vertical frame members 3 and 4. Preparatory to removing the sheet metal stamping from'the press the stamping is gripped between the fixed jaw 5 and the jaw 6 whichs pivotally supported upon the iixed jaw as at 1. AThe pvoted jaw 6 is opened and closed by means of an air motor in the form of a cylinder 8 piv- -otally supported as at on carriage member I2, `piston 9 and connecting rod l0 which is pivotally connected to the swinging jaw as at I I. The work gripping device, thatis, jaws 5 and 16, is supported upon a roller carriage, generally designated I5, by means of a tubular frame-work comprising a tubular arm I2 supported upon the carriage by the tubular members I3 and I4 which are rein- ;forced by braces I6 -and I1 respectively.

The roller carriage I5 comprises a rectangular metal frame-work supported upon the lower track .member 2 bywrollers I8 andV I9 and held in rolling' relation with the upper rail I by opposed rollers 20 and 2|. The carriage is also provided with rollers 22 which roll along the bottom face of the upper track I. From the above description it is evident that the carriage forms a cantilever suspension for the gripping jaws on the tracks I and 2.

The carriage I5 is arranged to be reciprocated upon tracks I and 2 by means of the arm 36 Xed on the horizontal shaft 3l which is journalled in support member 32. The outer end of the arm is provided with a roller 33 positioned between, and having a rolling contact with the vertical guide members 34 mounted upon the carriage I5. Since the gripping jaws must enter between the upper and lower dies of the press after the stamping operation to grip the work and remove the same, the movement of the gripping jaws must be synchronized with that of the press. By way of description the arm 30 will be actuated by the 4reciprocating die member of the press in the 4:form of ram 26, the lower die member is indicated i The driving connection between the ram 26'and the arm 30 takes the form of a cam plate 35 positively connected by means of rod 36 and arm 37 with the punch 26. Slide plate 35 is guided in its vertical reciprocation by the guide members .36. The slide member is provided with cams 33 and 46 which cooperate to form a cam way or track 4I for roller 42 mounted on arm 30. 'I'he slide plate 35 is also provided with a'cam 43 for roller 44 mounted on arm 30. The lower end of the slide plate 35 is provided with an approximately triangular opening 45 which is arranged fto cooperate with roller 46 mounted on arm 36.

A work knock-out device 41 is adjustably mounted on rod 48 fixed to the frame of the uploader.

The compressed air is supplied to the cylinder 8 by means of air line 50 which is connected with a source of compressed air (not shown). Air supply line 5U is connected through valve 5I either with air line 52, as shown in Fig. 4,

or with air line 53, as shown in Fig. 1.

As shown in Fig. 1, the press is closed, that is,

. the punch is lowered and the stamping operation -is completed. At this time line 52 is connected through valve 5I with air line 50 and the jaws 5 and 6 are opened. Slide plate 35 is at the bottom of its stroke with roller 42 about to enter cam way 4I. As the punch 26 starts its upward movement, slide plate 35 correspondingly moves upwardly. Roller 42 contacts cam surface 55 -thereby swinging arm 30 to the right, Fig. l, 55`

causing the carriage and jaws to advance between the upper and lower dies in work gripping position. The work or metal stamping is indicated at 56.

At this time the valve I is shifted so that air line 53 is connected with air line 50 and air line 52 is open to exhaust whereby the air motor closes the jaws which grip the work 56, see Fig. 4. As the die 26 and slide 35 continue their upward movement, roller 42 rolls out of cam way 4I and roller 44 rides on to cam surface 51 thereby causing the arm 30 to reverse its direction and now swing to the left or counterclockwise, as viewed in Fig. 4, thereby causing the carriage I5 to roll to the left and withdraw the work from the press. As roller 44 rides off of cam surface 51, roller 45 contacts slide 35 along the lower edge 58 of opening 45 thereby continuing the movement of the arm 30 and carriage I5 to the left until the die reaches its topmost position, Fig. 5. Just prior to reaching the work knock-out 41, valve 5I is reversed so that the air line 50 is now connected with line 52 and line 53 is open to exhaust thereby causing the air motor to open the jaws 5 and 5 to release the work. The work is ejected from the jaws by the work knock-out 41 and falls on to the conveyor 60.

The press is again loaded and the upper die 26 now starts on its downward stroke. At this time roller 46 rolls along the inclined edge 6I of opening 45 as the slide 35 travels downwardly with the upper die. This causes arm 30 to swing to the right or clockwise, Fig. 5, thereby rolling the carriage I5 along the tracks toward the die. At the end of the downstroke of the upper die 26 and slide 35, roller 46 approaches the end of the cam surface 6 I roller 42 is about to enter cam way 4I and the slide 35 and die 26 are about to reverse their direction and move upwardly to repeat the cycle of operation as above described.

Air valve 5I which is fastened to carriage I5 is equipped with offset actuating arms 62 and 63. Arms 62 and 63 are in diierent vertical planes. Cams 64 and 65 are fastened rigidly to upper track I. Cam 64 is in the same vertical plane as valve arm 62. Cam 65 is in the same vertical plane as valve arm 63. In closed position of dies 26 and 21, carriage and valve 5I have vposition as indicated in Fig. l. AS die 26 starts to raise and, as above described, advances the carriage I5 toward the press, valve arm 62 engages cam 64 throwing valve 5I, thus letting air to air line 53 thus closing the gripping jaws. Carriage I5 now reverses direction and the work is pulled from the press, the jaws remaining closed. Just before the removed panel meets knockout 41, valve arm 63 engages cam 65 and throws valve 5I to the opposite position, allowing air to flow into air line 52, thus opening the gripping jaws.

Shown on shaft 3l is a braking drum 10. A pair of brake shoe levers 1I are pivotally mounted as at 12 on arm 13. The brake shoe levers are yieldably forced against the brake drum to brake the same by means of the coil spring 14 supported between the head 15 of bolt 16 `and the lower brake shoe lever 1I. Bolt 16 is mounted on the upper lever 1I and passes freely through an opening in the lower arm 1I. This brake continuously brakes arm 35 and the carriage mechanism.

From observation of the up and down movement of a press, it can be seen that high accelerations and decelerations are evident in the movement. These same accelerations and decelerations are transferred to the 'unloader mechanism.

In fact, they are multiplied approximately three times in the unloader movement.

From further observation of the unloader mechanism it can be shown that the movement of arm at certain points in the cycle, that is, when arm 30 is being actuated by cams 51 or cam opening 45, is not entirely controlled. In other words, at these points, if due to press action, cam plate suddenly slows down, arm 30 and all carriage parts due to momentum are free to continue on at the last speed imparted by cam plate 35 to arm 30. This, of course, is undesirable and a continuous brake is necessary to hold arm 30 at all times against cam surfaces on plate 35. 'Ihe amount of brake effort used is just slightly more than that needed to give smooth action to the mechanism throughout the press cycle. When once adjusted the brake requires no attention and the energy it absorbs, due to the continuous braking, is dissipated as heat and lost into the air.

I claim:

l. In a press for stamping sheet material Vhavl ing relatively movable die members which upon closing stamp the sheet material and upon opening release the same, the combination of a reciprccable carriage, gripping means mounted on the carriage for gripping the stamping, a driving arm for said carriage pivotally mounted on a xed pivot, a connection between the free end of the arm and the carriage, and a cam plate adapted to be connected to the movable die member and arranged to reciprocate with the same acting upon the pivoted arm whereby the carriage moves the gripping means into the press as the dies open to grip the vstamping and then retracts the gripping means and stamping from the press as the dies continue their opening movement.

2. In a press for stamping sheet material having relatively movable die members which upon closing stamp the sheet material and uponfopening release the same, the combination -of a reciprocable carriage, gripping means imounted on the carriage for gripping the stamping, -a 'driving arm for said carriage pivotally mounted on a fixed pivot, a connection 'between the Ifree end of the arm and the carriage, a cam vplate arranged to travel upwardly and downwardly `and adapted to travel with the movable die member, said cam plate including a cam :surface acting upon the arm to move the arm and carriage toward the press during the initial upward movement of the die whereby the gripping means moves into the press and grips the-stamping, said cam plate also including a cam Vsurface for moving the arm and carriage away from the press as the die continues its upward movement whereby the stamping is withdrawn vfrom `the press.

3. In a press for stamping sheet material 'having relatively movable 4die members which upon closing stamp the vsheet material and uponopening release the same, the combination 'of areciprocable carriage, gripping `means mounted on the carriage forgripping the stamping, a driving arm for said carriage pivotally mounted on a fixed pivot, a connection between the free end of the arm and the carriage, Aa `cam plate arranged to travel upwardly and downwardly andadapted to travel with the, movable 'die member, :said cam plate including 'a `cam surface acting upon the arm to move the arm and carriage towardthe Vpress `during the Aini-tial upward movement of the -die Vwhereby the gripping means movesin'to the press and grips the stamping, said cam plate also including a cam surface for moving the arm and carriage away from the press as the die continues its upward movementl whereby the stamping is withdrawn from the press, said cam plate also including a cam surface acting against the arm on the down stroke of the cam plate to swing the arm and move the carriage toward the press.

4. In a. press for stamping sheet material having relatively movable die members which upon closing stamp the sheet material and upon opening release the same, the combination of a reciprocable carriage, gripping means mounted on the carriage for gripping the stamping, a pivoted arm for reciprocating said carriage, and cam plate means for swinging the arm toward the press as the dies open to permit the gripping means to grip the stamping Vanti then away from the press as the dies continue their opening movement whereby the gripping means withdraws the stamping from the press, and braking means for applying a continual braking action to said pivoted arm whereby a smooth driving action is effected between the pivoted arm and the reciprocating carriage.

5. In a press for stamping sheet material having relatively movable die members which upon closing stamp the sheet material and upon opening release the same, the combination of a reciprocable carriage, gripping means mounted on the carriage for gripping the stamping, a driving arm for said carriage pivotally mounted on a xed pivot, a connection between the free end of the arm and the carriage, a cam plate arranged to travel upwardly and downwardly and adapted to travel with the movable die member, said cam plate including a cam surface acting upon the arm to move the arm and carriage toward the press during the initial upward movement of the die whereby the gripping means moves into the press and grips the stamping, said cam plate also including a, cam surface for moving the arm and carriage away from the press as the die continues its upward movement whereby the stamping is withdrawn from the press, and braking means for applying a continual braking action to said pivoted arm whereby a smooth driving action is effected between the pivoted arm and the reciprocating carriage.

6. In a press for stamping sheet material having relative movable die members which upon closing stamp the sheet material and upon opening release the same, the combination of Aa reciprocable carriage, gripping means mounted on the carriage for gripping the stamping, a stationary cam plate, control means movable with said carriage for actuating said gripping means, said control means cooperating with said cam plate to actuate said gripping means as said carriage is reciprocated, a pivoted arm for reciprocating said carriage and means adapted for swinging the arm toward the press as the dies open to permit the gripping means to grip the stamping and then away from the press as the dies continue their opening movement whereby the gripping means withdraws the stamping from the press.

KENNETH CARLYLE BUTTERFIELD. 

